Field of the Invention
The present invention relates to a substrate processing system constituting, for example, part of a semiconductor manufacturing apparatus.
Background Art
Japanese Patent Laid-Open No. 2009-270758 discloses introducing an atmosphere gas concentrically into a heating furnace body so that the pressure in the heating furnace body is maintained higher than the pressure in a salt bath chamber. This enables avoiding corrosion of furnace members and disturbance of the atmosphere in the heating furnace caused by a gas generated from the salt bath vessel.
Japanese Patent Laid-Open No. 2005-83962 discloses an arrangement in which when a microcomputer receives a gas leak signal from a gas leak alarm, it energizes a shutoff valve by turning on a transistor. This shutoff valve is ordinarily opened/closed by means of a permanent magnet. A current is caused to flow for a moment in a direction as opposed to the direction of opening/closing by means of the permanent magnet to cancel out the magnetic force, thereby shutting off gas with spring pressure.
Japanese Patent Laid-Open No. 2003-140703 discloses an arrangement in which an interlock unit is detachably provided between an input unit and a magnet valve unit and (or) between the magnet valve unit and another adjacent magnet valve unit. Safety measures are thereby provided selectively on the desired magnetic valves and devices related to the magnetic valves.
In some cases of handling of a dangerous gas in a substrate processing system such as a semiconductor manufacturing apparatus, a gas sensor is provided in order to ensure the desired safety performance of the apparatus. An arrangement is known in which a controller receives a detection signal from a gas sensor and outputs a signal to a solenoid to control opening/closing of a gate.
A dangerous gas exists which is assigned a safety criterion at or below the detection limit of gas sensors on the market. It is necessary to prevent even a trace amount of such a dangerous gas from flowing out of a certain place into a particular chamber. Control with reference to an alarm signal from a gas sensor, however, does not ensure the desired safety performance of an apparatus using such a dangerous gas since flowing-out of a trace amount of the gas cannot be detected. It is thus difficult to secure the safety. In a case where a dangerous gas is detected with a gas sensor set in a place where flowing-in of a dangerous gas must be prevented, the dangerous gas is detected with the gas sensor only after the dangerous gas has leaked out. It cannot be said that a sufficiently high degree of security can be secured in this case. It is desirable to prevent flowing-out of the dangerous gas.
In such a situation, a gas is supplied to a first chamber not containing a dangerous gas to increase the pressure in the first chamber while gases in a second chamber adjacent to the first chamber and containing the dangerous gas are discharged to reduce the pressure in the second chamber. That is, the pressure in the second chamber is reduced relative to that in the adjacent chamber. Pressure meters are provided in the first and second chambers. A controller receives measurement results from the pressure meters, checks whether the pressure in the second chamber is sufficiently low in comparison with that in the first chamber, and opens a gate between the first and second chambers. The components can thus be arranged to manage the difference in pressure between the first and second chambers so that the dangerous gas does not move into the first chamber.